Space

Further Reading

Wideband Gapfiller System

The Wideband Gapfiller satellites will be the DoD's most capable and powerful communication satellite. The WGS will provide near-term continuation and augmentation of the services currently provided by the Defense Satellite Communications System (DSCS) and the Global Broadcast Service (GBS) Ka services currently provided by GBS payloads on UFO satellites. WGS is a high-capacity satellite communications system designed to support the warfighter with newer and far greater capabilities than those provided by current systems, yet it is compatible with existing control systems and terminals. WGS will provide two-way X-band and Ka-band communications as well as Ka-band broadcast services to US Armed Forces and other agencies worldwide.

The new Wideband Gapfiller satellites will complement the DSCS III Service Life Enhancement Program (SLEP) and GBS payloads, and offset the eventual decline in DSCS III capability. WGS will offer 4.875 GHz of instantaneous switchable bandwidth, thus each WGS can supply more than 10 times the capacity of a DSCS III Service Life Enhancement Program (SLEP) satellite. Together these assets will provide wideband services during the transition period between today's systems and the advent of the Objective X/Ka wideband system or Advanced Wideband System (AWS), which has merged with Transformational Communications System (TCS), in 2008-2009. The DSCS system will be replaced by five fully operational Wideband Gapfiller Satellites (WGS), each of which will be able to downlink 2.4 Gbps of data to tactical users. The very first Wideband Gapfiller in orbit will provide greater capability and bandwidth than all the DSCS satellites combined.

Until the future Advanced-EHF replacement to the MILSTAR comes on-line with its capability to transmit 1 Gbps, short-term solutions to the military's bandwidth shortfall will be needed, such as the Wideband Gapfiller, a lesser robust interim solution to AEHF, Global Broadcast System, and leasing options. Due to the early loss of a MILSTAR satellite, DOD committed to the purchase of 4 AEHF satellites plus one spare. DOD considered accelerating AEHF by 18 months but later agreed to have a 3-year gap from last MILSTAR and the first AEHF launch. This will place greater dependency on Wideband Gapfiller, Global Broadcast System, and leases.

The combination of the Wideband Gapfiller Satellites, DSCS satellites, GBS payloads, wideband payload and platform control assets, and earth terminals operating with them has been referred to as the Interim Wideband System (IWS). It will provide services to the US Department of Defense and the Ministry of Defense for Canada as well as other Government and Allied users under unstressed conditions. The Gapfiller System will support continuous 24 hour per day wideband satellite services to tactical users and some fixed infrastructure users. Limited protected services will be provided under conditions of stress to selected users employing terrestrial modems capable of providing protection against jamming. The combined wideband satellite communications system consists of space vehicles of multiple types, control terminals and facilities, and user terminals. The Wideband Gapfiller Satellite System is limited to the Gapfiller satellites and associated control equipment and software that augment currently existing facilities.

The DoD wideband satellite communications system consists of multiple types of military satellites, control facilities, and user terminals that comprise three distinct segments: (1) the User Terminal Segment, (2) the Space Segment, which consist of three Gapfiller Satellites in geo-synchronous orbit, each providing a two way X-band, a new two way military Ka-band, and broadcast Ka-band services, and (3) the Control Segment.

WGS satellites are a follow-on to the current Defense Satellite Communications System satellites, but they offer a tenfold capability improvement in available bandwidth. In addition to providing improvements in X-band capability, WGS satellites will also have a new Ka band capability that can be used for both two-way and Global Broadcast Service communications. To take advantage of WGS' increased capabilities, STAR-T will be upgraded by adding a fourth band (Ka), making it a quad-band terminal. The versatile reachback capability offered by the STAR-T/WGS combination strongly supports force-projection operations emphasized in both the Army's transformation strategy and Joint Vision 2020.

The Global Broadcast Service [GBS] augments and interfaces with other communications systems to provide a continuous, high-speed, one-way flow of high-volume information supporting routine operations, training and military exercises, special activities, crisis, situational awareness, weapons targeting, intelligence, and the transition to and conduct of operations short of nuclear war. The Global Broadcast Service space segment will be implemented in three phases. Phase I supported a continental United States (CONUS) testbed. Phase II is the GBS capability hosted on the last three UHF Follow-On (UFO) communications satellites. Launch of these satellites was completed in Fiscal Year 2000. Beginning in FY 2005 additional GBS Phase II coverage and capacity is provided by launch of three Wideband Gapfiller Satellite (WGS). Phase III is an Objective capability planned as part of the Advanced Wideband System (AWS) I FY 2009-Plus.

Gapfiller will provide an increase in access for both transportable/mobile and fixed users. At the same time, the expected number of Gapfiller satellites alone will not provide full 65N-to-65S worldwide coverage across all intended coverage areas and all longitudes. There will be a continuing need for these users to access the Gapfiller satellites and the two or more DSCS III SLEPs to provide worldwide coverage.

The Gapfiller satellites will serve as the means to continue and increase the capability of wideband services until the introduction of the Objective or Advanced Wideband System. The Gapfiller satellites must either be backward compatible with, or allow for the affordable upgrade of, the existing terminal populations in use with the DSCS and GBS systems.

If the WGS Program does not go forward, DoD satellite communication capabilities will be at risk
and will not be adequate to meet DoD's future and increasing communication requirements. No other alternatives to the WGS program have been identified by the MILSATCOM Joint Program Office (SMC/MCX).

The WGS consists of two segments. The Air Force is acquiring the satellite segment under the Federal Acquisition
Regulation Part 12 rules for commercial item acquisition. First launch is projected for 2QFY05 with the second and third
launches following at approximately six-month intervals. The Army is acquiring the ground control segment and the
MILSATCOM Joint Program Office is integrating the WGS and GBS space and ground segments.
The 2001 Defense Appropriations Act, signed on August 9, 2000, limited funding to two satellites. Subsequently, the
Office of the Secretary of Defense issued a Program Decision Memorandum on August 22, 2000, supplementing WGS
funding by $272.9M to ensure funding of the complete constellation of three satellites. In December 2003, the OSD
directed the acquisition of two additional WGS satellites. The Program Office projects launch of Satellites 4 and 5 in
FY09 and FY10, respectively.

The Program Office plan for WGS satellite launch is to integrate them on both Delta and Atlas Evolved Expendable
Launch Vehicles (EELVs). The first launch will be on Delta and the second on Atlas. Boeing added extra solar panels to
their original design, which added weight and changed the class of EELV. The availability of the launch vehicle and an
aggressive integration schedule, less than the normal 24 months, are sources of schedule risk.